Exchange of trace elements at the sediment-water interface during early diagenesis processes

1995 ◽  
Vol 46 (1) ◽  
pp. 19 ◽  
Author(s):  
W Petersen ◽  
K Wallman ◽  
L Pinglin ◽  
F Schroeder ◽  
HD Knauth
Keyword(s):  
Trace Elements ◽  
Sediment Cores ◽  
Early Diagenesis ◽  
Water Phase ◽  
Laboratory Simulation ◽  
Sediment Surface ◽  
Water Interface ◽  
Large Area ◽  
Overlying Water ◽  
River Elbe

The exchange processes at the sediment-water interface can significantly influence the transport of trace contaminants in a river. In order to investigate the importance of these processes in the tidal part of the River Elbe, a laboratory 'simulation' apparatus (LABOSI) was used that allows the incubation of undisturbed sediment cores with a relatively large area (1700 cm²) in a closed system under defined conditions (temperature, pH, pE, etc.). Together with measured depth profiles of the pore-water and the solids of the incubated cores before and after the experiment, this method allows all relevant processes to be investigated in all three phases (sediment, overlying water, gas) simultaneously. Under oxic conditions, a flux of heavy metals (Cu, Cd , Zn) into the water phase was observed as a result of the mineralization of organic matter in the thin oxic layer of the sediment (thickness about 3 mm) as well as a flux of manganese caused by diffusion from deeper anoxic layers. Up to 40% of Cd, Zn and Ni and 15% of Zn deposited in the sediment by settling of contaminated suspended particulate matter can be remobilized from the sediment surface by the processes of early diagenesis. Within 14 days, an enrichment of arsenic in the sediment surface caused by diffusion from deeper anoxic layers could be detected. Under anoxic conditions and when the other electron acceptors were consumed, Fe(II) was released and accompanied by a strong remobilization of As, Co and Cr and an accelerated release of Mn(II). This release was soon stopped when the water phase became oxic again, and the trace elements were removed from the water phase by co-precipitation andlor adsorption on the freshly formed hydrous ferric oxides.

Pigment Preservation in Lake Sediments: A Comparison of Sedimentary Environments in Trout Lake, Wisconsin

1991 ◽  
Vol 48 (3) ◽  
pp. 472-486 ◽  
Author(s):  
James P. Hurley ◽  
David E. Armstrong
Keyword(s):  
Accumulation Rate ◽  
Sediment Cores ◽  
Sediment Accumulation ◽  
Sediment Surface ◽  
Water Interface ◽  
Sedimentary Pigments ◽  
Sedimentary Environments ◽  
Trout Lake ◽  
Secondary Carotenoids ◽  
Β Carotene

Fluxes and concentrations of a phorbins and major algal carotenoids were quantified in sediment trap material and sediment cores from two basins of Trout Lake, Wisconsin (TrDH and TrAB). The basins were chosen to contrast the influence of oxygen content at the sediment–water interface (TrDH, oxic and TrAB, reducing), sediment accumulation rate, and focusing. Pigment diagenesis occurred in both basins, but transformations and destruction were more extensive in TrDH. Although untransformed chlorophyll a was the major phorbin deposited at the sediment surface of both basins (51–64 mol%), pigment destruction, coupled with transition to pheophytin, accounted for substantial losses, especially in oxic TrDH sediments. Fucoxanthin, peridinin, and diadinoxanthin, despite representing > 70% of the deposited carotenoid flux, were substantially degraded or transformed in both basins. However, preservation was relatively high for secondary carotenoids, such as diatoxanthin and β-carotene, and for a major cryptomonad pigment, alloxanthin. Residual profiles in sediments show that pigment sedimentation from the epilimnion and accumulation in the permanent sediments are not directly related and that diagenesis must be considered in interpreting sedimentary pigments.

scholarly journals Behaviour of Metal(loid)s at the Sediment-Water Interface in an Aquaculture Lagoon Environment (Grado Lagoon, Northern Adriatic Sea, Italy)

2021 ◽  
Vol 11 (5) ◽  
pp. 2350
Author(s):  
Elisa Petranich ◽  
Matteo Crosera ◽  
Elena Pavoni ◽  
Jadran Faganeli ◽  
Stefano Covelli
Keyword(s):  
Sediment Cores ◽  
Fish Farm ◽  
Trophic Chain ◽  
Water Interface ◽  
Northern Adriatic Sea ◽  
Overlying Water ◽  
Northern Adriatic ◽  
In Situ Experiments ◽  
Diffusive Fluxes ◽  
Lagoon Environment

The cycling of metal(loid)s at the sediment–water interface (SWI) was evaluated at two selected sites (VN1 and VN3) in an active fish farm in the Grado Lagoon (Northern Adriatic, Italy). In situ experiments using a transparent benthic chamber and the collection of short sediment cores were performed, to investigate the behavior of metal(loid)s in the solid (sediments) and dissolved (porewaters) phases. Total and labile concentration of metal(loid)s were also determined in sediments, to quantify their potential mobility. Comparable total concentrations were found at both sites, excluding As, Mn, Pb and V, which were higher at VN3. Metal(loid) porewater profiles showed a diagenetic sequence and a close dependence with redox (suboxic/anoxic) conditions in the surface sediments. Positive diffusive fluxes along with benthic fluxes, particularly at the more oxic site, VN1, were found for almost all metal(loid)s, indicating their tendency to migrate towards the overlying water column. Despite sediments at two sites exhibiting high total metal(loid) concentrations and moderate effluxes at the SWI, the results suggest that they are hardly remobilized from the sediments. Recycling of metal(loid)s from the SWI would not constitute a threat for the aquatic trophic chain in the fish farm.

Molecular diffusive fluxes of oxygen in sediments of Port Phillip Bay in south-eastern Australia

1999 ◽  
Vol 50 (6) ◽  
pp. 557 ◽  
Author(s):  
Christopher M. Burke
Keyword(s):  
Sediment Cores ◽  
Sediment Surface ◽  
Overlying Water ◽  
South Eastern ◽  
Eastern Australia ◽  
Oxygen Cycling ◽  
Diffusive Fluxes ◽  
High Degree ◽  
South Eastern Australia

Port Phillip Bay is a large, shallow, semi-enclosed bay in south-eastern Australia. Micro- electrodes were used to measure profiles of oxygen concentration in sediment cores taken from nine sites in the bay in January and February 1994. The effects of sediment surface topography, flow rate of the overlying water and irradiance on the distribution of oxygen in the sediments, and on the molecular diffusive fluxes of oxygen, were determined. Oxygen typically penetrated ≤3 mm into the sediment. Deeper penetration occurred when oxygen was photosynthetically produced in situ. In most cores the sediments consumed oxygen. Molecular diffusive fluxes of oxygen, determined from the gradient of oxygen in the DBL, were compared with fluxes modelled from the sediment gradient of oxygen. The modelled diffusive fluxes are considered to give better estimates of the diffusive fluxes in situ. Modelled fluxes ranged from 1.5 to 28.5 mmol O2 m–2 day–1, which was 43% (s.d. = 36%, n = 16) of the total flux at each site. Cores from two sites demonstrated efflux of oxygen, up to 71 mmol O2 m–2 day–1, as a result of photosynthesis in situ. The high degree of variability in oxygen fluxes within cores demonstrates the dynamism of oxygen cycling in these sediments.

scholarly journals High spatial resolution analysis of the distribution of sulfate reduction and sulfide oxidation in hypoxic sediment in a eutrophic estuary

2016 ◽  
Vol 75 (2) ◽  
pp. 418-426
Author(s):  
Rathnayake M. L. D. Rathnayake ◽  
Shogo Sugahara ◽  
Hideaki Maki ◽  
Gen Kanaya ◽  
Yasushi Seike ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Spatial Resolution ◽  
Sediment Cores ◽  
Sulfide Oxidation ◽  
Sulfur Cycle ◽  
Sediment Surface ◽  
Concentration Profiles ◽  
Overlying Water ◽  
Global Environmental Issue ◽  
H2s Production

Bottom hypoxia and consequential hydrogen sulfide (H2S) release from sediment in eutrophic estuaries is a major global environmental issue. We investigated dissolved oxygen, pH and H2S concentration profiles with microsensors and by sectioning sediment cores followed by colorimetric analysis. The results of these analyses were then compared with the physicochemical properties of the bottom water and sediment samples to determine their relationships with H2S production in sediment. High organic matter and fine particle composition of the sediment reduced the oxidation-reduction potential, stimulating H2S production. Use of a microsensor enabled measurement of H2S concentration profiles with submillimetre resolution, whereas the conventional sediment-sectioning method gave H2S measurements with a spatial resolution of 10 mm. Furthermore, microsensor measurements revealed H2S consumption occurring at the sediment surface in both the microbial mat and the sediment anoxic layer, which were not observed with sectioning. This H2S consumption prevented H2S release into the overlying water. However, the microsensor measurements had the potential to underestimate H2S concentrations. We propose that a combination of several techniques to measure microbial activity and determine its relationships with physicochemical properties of the sediment is essential to understanding the sulfur cycle under hypoxic conditions in eutrophic sediments.

Estimation of Nitrogen and Phosphorus Release Rates at Sediment-Water Interface of Nansi Lake, China

2012 ◽  
Vol 573-574 ◽  
pp. 573-577
Author(s):  
Bao Li ◽  
Zhi Qi Wang
Keyword(s):  
Water Body ◽  
Lake Restoration ◽  
Sediment Cores ◽  
Sampling Period ◽  
Phosphorus Release ◽  
Water Interface ◽  
Nansi Lake ◽  
Release Rates ◽  
Nitrogen And Phosphorus ◽  
Overlying Water

At present, Nansi Lake restoration is maily focused on reducing extraneous pollution, however, it is unclear about the endogenous pollution. In this study, twelve intact sediment cores were collected from four sub-lakes (Nanyang Lake, Dushan Lake, Zhaoyang Lake and Weishan Lake) in Nansi Lake, and the fluxes of NH4+-N, PO43--P, NO3--N, TN and TP at sediment-water interface were calculated based on static incubation of sediment cores with a laboratory-scale benthic chamber. The incubation results showed fluxes of PO43--P, NO3--N, TN and TP in Nanyang Lake were the highest and as follows: 2.73, 7.55, 44.43 and 3.06 mg/m2.d, respectivly, and the flux of NH4+-N in Nanyang Lake, Dushan Lake and Zhaoyang Lake had little difference ranged from 8.99 to 10.19 mg/m2.d. This study indicated that during the sampling period sediment acted as a source of nitrogen as well as phosphorus to the overlying water body in Nansi Lake.

Effects of Fe addition on sediment P dynamics in a eutrophic lake

2021 ◽  
Author(s):  
Melanie Münch ◽  
Rianne van Kaam ◽  
Karel As ◽  
Stefan Peiffer ◽  
Gerard ter Heerdt ◽  
...  
Keyword(s):  
Water Quality ◽  
Organic Matter ◽  
Surface Water ◽  
Water Column ◽  
Sediment Cores ◽  
Surface Water Quality ◽  
Water Interface ◽  
Eutrophic Lakes ◽  
Fe Addition

<p>The decline of surface water quality due to excess phosphorus (P) input is a global problem of increasing urgency. Finding sustainable measures to restore the surface water quality of eutrophic lakes with respect to P, other than by decreasing P inputs, remains a challenge. The addition of iron (Fe) salts has been shown to be effective in removing dissolved phosphate from the water column of eutrophic lakes. However, the resulting changes in biogeochemical processes in sediments as well as the long-term effects of Fe additions on P dynamics in both sediments and the water column are not well understood.</p><p>In this study, we assess the impact of past Fe additions on the sediment P biogeochemistry of Lake Terra Nova, a well-mixed shallow peat lake in the Netherlands. The Fe-treatment in 2010 efficiently reduced P release from the sediments to the surface waters for 6 years. Since then, the internal sediment P source in the lake has been increasing again with a growing trend over the years.</p><p>In 2020, we sampled sediments at three locations in Terra Nova, of which one received two times more Fe during treatment than the other two. Sediment cores from all sites were sectioned under oxygen-free conditions. Both the porewaters and sediments were analysed for their chemical composition, with sequential extractions providing insight into the sediment forms of P and Fe. Additional sediment cores were incubated under oxic and anoxic conditions and the respective fluxes of P and Fe across the sediment water interface were measured.</p><p>The results suggest that Fe and P dynamics in the lake sediments are strongly coupled. We also find that the P dynamics are sensitive to the amount of Fe supplied, even though enhanced burial of P in the sediment was not detected. The results of the sequential extraction procedure for P, which distinguishes P associated with humic acids and Fe oxides, as well as reduced flux of Fe(II) across the sediment water interface in the anoxic incubations, suggest a major role of organic matter in the interaction of Fe and P in these sediments.</p><p>Further research will include investigations of the role of organic matter and sulphur in determining the success of Fe-treatment in sequestering P in lake sediments. Based on these data in combination with reactive transport modelling we aim to constrain conditions for successful lake restoration through Fe addition.</p>

scholarly journals Oxygenation of anoxic sediments triggers hatching of zooplankton eggs

2015 ◽  
Vol 282 (1817) ◽  
pp. 20152025 ◽  
Author(s):  
Elias Broman ◽  
Martin Brüsin ◽  
Mark Dopson ◽  
Samuel Hylander
Keyword(s):  
Sediment Surface ◽  
Substantial Part ◽  
System Modelling ◽  
Anoxic Sediments ◽  
Overlying Water ◽  
Pelagic Copepod ◽  
Coastal Marine ◽  
Copepod Population ◽  
Benthic Pelagic Coupling ◽  
Dormant Eggs

Many coastal marine systems have extensive areas with anoxic sediments and it is not well known how these conditions affect the benthic–pelagic coupling. Zooplankton lay their eggs in the pelagic zone, and some sink and lie dormant in the sediment, before hatched zooplankton return to the water column. In this study, we investigated how oxygenation of long-term anoxic sediments affects the hatching frequency of dormant zooplankton eggs. Anoxic sediments from the brackish Baltic Sea were sampled and incubated for 26 days with constant aeration whereby, the sediment surface and the overlying water were turned oxic. Newly hatched rotifers and copepod nauplii (juveniles) were observed after 5 and 8 days, respectively. Approximately 1.5 × 10 5 nauplii m −2 emerged from sediment turned oxic compared with 0.02 × 10 5 m −2 from controls maintained anoxic. This study demonstrated that re-oxygenation of anoxic sediments activated a large pool of buried zooplankton eggs, strengthening the benthic–pelagic coupling of the system. Modelling of the studied anoxic zone suggested that a substantial part of the pelagic copepod population can derive from hatching of dormant eggs. We suggest that this process should be included in future studies to understand population dynamics and carbon flows in marine pelagic systems.

scholarly journals Sediment-water column fluxes of carbon, oxygen and nutrients in Bedford Basin, Nova Scotia, inferred from <sup>224</sup>Ra measurements

2013 ◽  
Vol 10 (1) ◽  
pp. 53-66 ◽  
Author(s):  
W. J. Burt ◽  
H. Thomas ◽  
K. Fennel ◽  
E. Horne
Keyword(s):  
Organic Matter ◽  
Nova Scotia ◽  
Water Column ◽  
Explicit Knowledge ◽  
Dissolved Inorganic Carbon ◽  
Chemical Constituents ◽  
Water Interface ◽  
Benthic Fluxes ◽  
Pore Waters ◽  
Overlying Water

Abstract. Exchanges between sediment pore waters and the overlying water column play a significant role in the chemical budgets of many important chemical constituents. Direct quantification of such benthic fluxes requires explicit knowledge of the sediment properties and biogeochemistry. Alternatively, changes in water-column properties near the sediment-water interface can be exploited to gain insight into the sediment biogeochemistry and benthic fluxes. Here, we apply a 1-D diffusive mixing model to near-bottom water-column profiles of 224Ra activity in order to yield vertical eddy diffusivities (KZ), based upon which we assess the diffusive exchange of dissolved inorganic carbon (DIC), nutrients and oxygen (O2), across the sediment-water interface in a coastal inlet, Bedford Basin, Nova Scotia, Canada. Numerical model results are consistent with the assumptions regarding a constant, single benthic source of 224Ra, the lack of mixing by advective processes, and a predominantly benthic source and sink of DIC and O2, respectively, with minimal water-column respiration in the deep waters of Bedford Basin. Near-bottom observations of DIC, O2 and nutrients provide flux ratios similar to Redfield values, suggesting that benthic respiration of primarily marine organic matter is the dominant driver. Furthermore, a relative deficit of nitrate in the observed flux ratios indicates that denitrification also plays a role in the oxidation of organic matter, although its occurrence was not strong enough to allow us to detect the corresponding AT fluxes out of the sediment. Finally, comparison with other carbon sources reveal the observed benthic DIC release as a significant contributor to the Bedford Basin carbon system.

Dissolved Inorganic Nitrogen Fluxes at Sediment-Water Interface in Yangtze Estuarine Tidal Flat

2013 ◽  
Vol 726-731 ◽  
pp. 288-295 ◽  
Author(s):  
Huan Guang Deng ◽  
Dong Qi Wang ◽  
Zhen Lou Chen
Keyword(s):  
Tidal Flat ◽  
Environmental Gradients ◽  
Inorganic Nitrogen ◽  
Yangtze Estuary ◽  
Water Interface ◽  
Dissolved Inorganic Nitrogen ◽  
Overlying Water ◽  
Spatial Differences ◽  
Estuary Sediment ◽  
Temporal And Spatial

Yangtze estuary data, collected over three years, indicates that the temporal and spatial distributions of the environmental gradients reflect complicated seasonal changes and spatial differences in the exchange flux of the dissolved inorganic nitrogen (DIN= NH4++ NO3-+ NO2-) across the sediment-water interface. Overall in northern sites of Yangtze estuary, sediment was a source of ammonium (NH4+) (-3.67~10.65 mmol·m-2·d-1) probably because of higher salinities. Sediment was a sink for NH4+ in southern sites (-18.45~3.33 mmol·m-2·d-1) during most years. The exchange behavior of nitrate (NO3-) showed temporal and spatial variation from the upper to lower estuary and ranged from-32.8 mmol·m-2·d-1 to 35.8 mmol·m-2·d-1. The interface exchange direction of ammonium was affected by NH4+ concentration, but the relationship between NO3- concentration and the direction of flux was not obvious. The concentration of nitrite (NO2-) was very low and its interface flux was not related to DIN concentration. Overall, the sediment of Yangtze Estuarine tidal flat was a source of DIN to overlying water in the spring, but a sink for DIN during the other three seasons of the year.

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